1. Field of the Invention
This invention relates to a fuel cap having a pressure control valve that controls the pressure within a fuel tank.
2. Description of the Related Art
A fuel cap is disclosed in JP-A 2005-81862. The fuel cap is provided with a cap main body that is screwed onto an inlet of a fuel tank and a pressure control valve attached to the cap main body that controls the pressure within the fuel tank. The pressure control valve, comprising a plurality of valve bodies having positive and negative pressure valves, controls the pressure inside the tank within a specified range by having the positive valve open when the pressure inside the tank exceeds a specified value and the negative valve open when the pressure drops below the value. The valve body of the pressure control valve delivers enhanced sealing performance by being made of rubber. On the valve body, two seating portions are provided side by side on the same seating surface where the seal portions of the positive and negative pressure valves are respectively seated or disseated.
In such pressure control valve, if a sizable elastic deformation occurs at the seating portion of the valve body made of rubber, the deformation may be transferred to the other adjacent seating portion to impair the sealing performance. The elastic deformation of the seating portion of the valve body has a significant impact especially on the pressure control valve with specifications that require a high valve-opening pressure.